Ishii et al., in J. Org. Chem., 1993, 58, 4497, reports the synthesis of cyclopentenone derivatives from the reaction of a ketone with two equivalents of an aldehyde or by the reaction of an enone with an aldehyde, which is catalyzed by Zirconium chloride derivatives such as ZrOCl2 or ZrCl4, the oxide being described as the best catalyst.
However, the procedure reported by Ishii requires severe conditions such as high temperature (between 130 and 200° C., the upper part of the range giving the best results, see Table I). Such severe conditions may result in poor yields (for example 17% when all the ring substituents are methyl groups, reaction carried out at 200° C.). These conditions are not of high industrial interest since are not environmentally friendly, and require much energy and produce high amounts of wastes.